REASON 27:Romney wants to nullify the Environmental Protection Agency's power to regulate greenhouse gases under the Clean Air Act. The Clean Air act, as it stands, is projected to result in a net improvement of thirty to one in U.S. economic growth, with $2 trillion in benefits.

If you’ve read the other Reasons on this site, you’ll have noticed that only one of them is even vaguely connected with the environment: Obama’s success in mandating better vehicle fuel efficiency. There’s no whitewashing the fact that his presidency hasn’t been a green one, at least not yet. Our opportunity to elect a genuinely green President was in 2000—an opportunity torpedoed (this really bears repeating) by the Green Party candidate. Voters who care strongly about the environment have already let the perfect be the enemy of the good, with calamitous results. If you’re one of those voters, please ask yourself: Can we afford to do it again?

I never expected Obama to be actively environmentalist—he was a senator from a big coal-producing state—and so I’ve been less prone to disappointment with him than my progressive friends have been. What he has been, demonstrably, is passively environmentalist. Unlike his predecessor, he has left our country’s pretty good system of environmental and land-use protections in place, and when he’s seen an opportunity to do the environment a good turn without paying too steep a political price (as when he delayed a decision on the disastrous Keystone oil-sands pipeline), he has taken it.

If you hoped Obama would expend political capital on transformative climate-change legislation, I can understand your disappointment, but your hopes seem to me misplaced. I think he did the right thing in making the Affordable Care Act the centerpiece of his first term, and the economic catastrophe he inherited from George Bush made it simply impossible for him to take on climate change as well. But I do have some hope that he’ll do it in his second term. He’s trying very hard to do what’s best for the country, and he’s a very smart man, and a smart man can see that climate change is a serious long-term threat.

So give Obama a C-plus or even just a C on the environment if you like. But consider that Mitt Romney, if he’s elected, will nullify soundly based decisions by the EPA; he will continue to pretend that the science of climate change is uncertain; he will open up all federal lands (except, presumably, national parks) to the ravages of drilling and mining; he will roll back sensible regulation of pollution and habitat destruction; and he has shown, with his choice of Paul Ryan as a running mate, that he is serious about slashing funding for every federal program except the military—and you’d better believe that the EPA and Fish and Wildlife will be the first to be gutted. Mitt Romney will get an F, double-underlined in red ink.